The market never opened on 9/11....the futures traded a bit I think. When it did re-open the cash mkt slid about 150 points in a few days. The amrket was already in a pretty nice downtrend, so shorts made some decent money. Although, I'm sure most people would give it all back to erase the events of that day. I know I would.
So if somebody was long, and you had stops a few points back...it gapped down at the reopen...well then you're gonna hurt a bit.